Oxygen is produced commercially in large quantities by the cryogenic separation of air, generally employing a double column arrangement having a higher pressure column in heat exchange relation with a lower pressure column. A recent significant advancement in the production of oxygen is the side column system which enables the production of oxygen with lower operating costs. Examples of side column systems may be found in U.S. Pat. No. 5,463,871--Cheung and U.S. Pat. No. 5,582,036--Drnevich et al.
When the production of elevated pressure oxygen is desired using the side column system, liquid oxygen from the side column is pumped and then vaporized against boosted feed air. The air pressure for the booster air compressor may fluctuate especially where the base load air compressor is also supplying air for another use such as the blast air for a blast furnace. Such fluctuations result in unstable operation.
Accordingly it is an object of this invention to provide a cryogenic air separation system using a side column arrangement which can produce oxygen with improved stability.